Field of the Invention
The present invention relates to a gear unit used for driving a developer bearing member. The present invention also relates to a process cartridge and an image forming apparatus using a gear unit. In particular, the present invention is suitably applied to a color electrophotographic image forming apparatus.
Herein, an electrophotographic image forming apparatus is an image forming apparatus that forms images on recording materials by using an electrophotographic image forming system. Examples of the electrophotographic image forming apparatus include an electrophotographic copying machine, an electrophotographic printer (a laser beam printer, an LED printer, etc.), a facsimile apparatus, and a word processor.
The aforementioned process cartridge includes at least an image bearing member. In many cases, the process cartridge includes an image bearing member and a process unit. The process unit includes at least one of a charging unit, a developing unit, and a cleaning unit. The process cartridge is attachable to and detachable from a main body of the image forming apparatus.
A developing device includes at least a developer bearing member for developing electrostatic images. A developing frame supporting the developer bearing member and other elements are integrated to form the developing device. The developing device is also attachable to and detachable from the main body of the image forming apparatus.
Description of the Related Art
Conventional electrophotographic image forming apparatuses using an electrophotographic image forming system adopt a process cartridge system. In such an image forming apparatus, an electrophotographic photosensitive drum and a process unit that acts thereon are integrated into a cartridge, which is attachable to and detachable from a main body of the image forming apparatus. With the process cartridge system, users can perform maintenance of the apparatus by themselves without relying on a repairperson. As a result, usability of the apparatus has significantly improved. Thus, the process cartridge system is adopted in many electrophotographic image forming apparatuses.
Japanese Patent Application Laid-Open No. 2009-288286 discusses a method for assembling a developing device included in a process cartridge, in which, when a developing roller or the like is attached to a developer container, both ends of the shaft of the developing roller are rotatably supported by bearings. In such a case, the bearings are fixed to the developer container with screws. In addition, a plurality of gears is rotatably attached to the bearings fixed to the developer container. In addition, a cover member for covering the gears is fixed to the bearings with screws.
However, when such a developing device is assembled, if the bearings, the gears, and the cover member are sequentially attached to the developer container, many assembly steps are required. As a result, since the number of devices to be assembled is increased, the complexity of the assembly work may be increased and the costs may be increased.